1. Field of Invention
The present invention relates to a gas generator and a restraining device using the same.
2. Description of the Related Art
There is known a fact that when a gas generator installed in a vehicle is activated, an output pressure changes with the environmental temperature (for example, the output pressure of the gas generator is slightly high when the temperature is high, and the output pressure of the gas generator is slightly low when the temperature is low), thus a method of controlling the combustion internal pressure inside a housing of a gas generator is adopted in order to restrain such changes.
JP-A No. 2003-34219 discloses a gas generator in which gas discharge ports 126a, 126b having two different diameters are formed in a housing and sealed by sealing tapes 27. The sealing tape that covers the port 126a having larger open area ruptures at lower pressure, and, as described in the specification, “[0034] Furthermore, even when the housing is provided with only a single combustion chamber, only the gas discharge port having larger open area is opened when the external environmental temperature is low when the gas generator is activated, and both the gas discharge port having larger open area and the gas discharge port having smaller open area are opened when the external environmental temperature is an ambient temperature or high temperature, whereby more stable combustion internal pressure can be obtained.” In this case, when the housing internal pressure is increased during a combustion under a high temperature, it is inhibited that a burning rate of the gas generating agent is accelerated to increase the output pressure more than the that obtained in the combustion under an ambient temperature or a low temperature.
JP-A No. 2004-82995 discloses a mechanism for continuously changing the amount of filters covering a periphery of the gas discharge ports to thereby change the output pressure. For example, by using a signal sent from a sensor for detecting the sitting state or the weight of the occupant, the amount of filters closing the gas discharge ports is changed, and the temperature of gas to be discharged is adjusted, whereby the output pressure is controlled.